By JAKE ELLISON, SEATTLEPI.COM STAFF

Published 10:01 pm, Wednesday, January 16, 2013

With more than 130 arrests for suspected driving under the influence of drugs in the state (16 in King County) since marijuana possession became legal on Dec. 6, it's likely the first DUI charge for driving while having a blood level of 5 nanograms or more of THC is in the pipeline.

The blood samples from those suspected drug DUIs are currently at the state's toxicology lab and should be reported back to the law enforcement official within the next few weeks, said Sgt. Paul Erdahl, a spokesman for the Washington State Patrol. The state has made 1,355 alcohol DUI arrests, with 240 in King County during the same period.

A Seattle attorney whose practice consists solely of medical marijuana cases said more people are coming to him for help fighting charges of driving under the influence of marijuana, even before the new limit took effect.

"I'm seeing one to two a month and have been for a year," attorney Aaron Pelley said."Prior to that, I didn't see really any."

Pelley believes state patrol officers had been ramping up their enforcement of "green DUIs" in anticipation of the passage of I-502, the law making possession of up to an ounce of marijuana legal. And, now that it's on the books, he suspects there's been a "huge spike of number of people being tested."

"It's not very often you give law enforcement a tool and they don't use it," he said.

I-502 established for the first time a limit for the amount of active THC, the chemical in pot that makes you high, you can have in your blood stream while driving.

Five nanograms or more, and you can be charged with a DUI.

That part of the law was the most contentious among supporters of legal pot. Medical marijuana users worried that the establishment of a legal limit would lead to more arrests and convictions for DUI, even when the person with THC in the blood isn't high.

The architects of I-502 argued the limit makes sense because, one, voters wanted to make sure people weren't driving high on all that legal pot, and, two, the body gets rid of active THC within hours of ingesting marijuana.

"Even heavy marijuana users like medical marijuana patients should have their THC levels drop below 5 ng/mL if they wait a few hours before driving," the group said on its I-502 website.

Nevertheless, Pelley said, the law has made his job harder because before there was a legal limit, like the .08 limit for alcohol, he could argue that his clients were not "appreciably affected" by the drug in their system.

But with the limit, that argument is harder to make. In fact, get caught with over 5 nanograms in your blood and you're considered impaired "per se" or in fact.

Pelley adds, however, defense lawyers can still challenge a charge based the probable cause an officer established to make you take a blood test.

Before the law, just having marijuana in the vehicle or smelling like it could be probable cause. Now, though, officers have to use their full battery of tests to establish probable cause for a driver being "appreciably affected" or driving under the influence.